1. Field of the Invention
This invention relates to a method and apparatus for cutting holes in glass sheets and, in particular, cutting pattern shaped holes.
2. Description of the Technical Problems
Pattern shaped holes in glass sheets are difficult to produce consistently, even under favorable circumstances. Although conventional scoring has been used to cut internal patterns, once the pattern is scored in the glass, removing the center portion becomes a problem. Damage is often caused to the exterior periphery portion which is the very portion desired to be preserved. Highly skilled experts have, in some cases, been able to cut holes in glass with conventional scoring and breakout; however, such methods are not practical for mass production.
A number of methods for producing circular holes in glass have been developed. One such apparatus is disclosed in U.S. Pat. No. 4,297,059 to Miyanaga. The Miyanaga invention produces a circular cut in the glass to a predetermined depth. After the cut has been made, the apparatus is removed and the glass is struck adjacent to the circular cut in order to break loose the glass disc enclosed by the cut. The edge or margin of the hole is then smoothed by grinding or polishing. The Miyanaga patent teaches rotating a circular saw or glass cutter in order to cut the glass.
An attempt to produce oval holes in glass sheets is shown in U.S. Pat. No. 3,845,676 to Pierce. The Pierce apparatus provides a device for cutting ovals or circles in sheet material, but does not provide for the breakout of the hole or pattern cut made by the operation of the device.
One of the main problems with the breakout as previously mentioned is that the edge portion which is intended to be saved is often destroyed unless great care is taken that the score produced in the glass does not run through the edge portion.
A number of inventions have been made to produce pattern shaped glass pieces; however, the purpose of those inventions is to produce a pattern shaped piece, not a hole, and the edge portion is removed rather than preserved.
One method for making a pattern piece of glass which produces a wasted edge portion in shown in U.S. Pat. No. 3,178,085 to Jochim. The Jochim device is a method and apparatus to provide a scoring of the pattern with the subsequent pressing of the glass in "cookie cutter" fashion to sever the edge portion from the pattern piece to be saved.